The Mack truck would have the greater force of impact due to its size and higher center of gravity. The mini cooper would have the greater impulse because it is much smaller and lighter than a Mack truck. The mini cooper would also have a greater change in momentum because it is lighter and the impact from the Mack truck would cause a stronger force into the mini cooper.
The mack truck would have the greater deceleration because it is much heavier and it would take a lot more time to slow down.